Patent Application
20080007501
Controller 12 may include a light source 20, a light modulator 21, and computer operable instructions 22 that receive input data 24 and convert the input data 24 into input light image 14. Modulator 21 may provide a modulated image by turning light on and off, wherein the image subframes may be synchronized to the rotational position of image shifter 18. Image subframes are described in detail in U.S. Pat. No. 7,030,894, entitled IMAGE DISPLAY SYSTEM AND METHOD, issued on Apr. 18, 2006, and hereby incorporated by reference in its entirety herein. Modulator 21 may be a light modulator as described in U.S. Pat. No. 7,030,894 B2, entitled IMAGE DISPLAY SYSTEM AND METHOD, issued on Apr. 18, 2006, and hereby incorporated by reference in its entirety herein. Input image 14 may comprise a single image from an electronic video data stream including a continuous stream of input images. Input light image 14 may be positioned at an angle 26 with respect to a plane 36 in a range of five to eighty five degrees, for example. In the embodiment shown in
Image shifter 18 may be mounted on a shaft, such as a rigid shaft 28, connected to an actuator, such as a motor 30, wherein motor 30 rotates shaft 28 about a rotational axis 32 extending along shaft 28. Due to the rigid nature of shaft 28, external disturbances may not appreciably affect an image 38 output by display system 10. Motor 30 may be a dc motor, a stepper motor, or any other device operable to rotate shaft 28 about axis 32. Motor 30 may rotate shaft 28 and image shifter 18 continuously or between predetermined stop positions wherein the image shifter 18 remains at the stop position for a predetermined dwell time. Rotation of motor 30 in a continuous or step wise fashion may utilize reduced drive circuitry, thereby decreasing the cost of the display system of the present invention, when compared to systems of the prior art. Moreover, due to the rotational nature of the actuator or motor 30 utilized in the present invention, motor 30 may have a relatively small noise output when compared to back and forth reciprocating actuators of the prior art.
Image shifter 18 is mounted on shaft 28 such that image shifting surface 16 of image shifter 18 is positioned at an angle 34 with respect to a plane 36 positioned perpendicular to rotational axis 32. In one embodiment, angle 34 of image shifting surface 16 may be parallel to a back surface 18a of image shifter 18, wherein the entire image shifter is mounted at an angle 34, with respect to plane 36, on shaft 28. In another embodiment, angle 34 of image shifting surface 16 may be positioned at an angle 34 with respect to back surface 18a of image shifter 18 such that back surface 18a of image shifter 18 is mounted on shaft 28 perpendicular to rotational axis 32 and parallel to plane 36. Other embodiments may also be utilized to position image shifting surface 16 at desired angle 34 with respect to plane 36 and rotational axis 32.
Angle 34 may be chosen to result in an output image 38 received on an image plane 40 from image shifting surface 16 that is deflected a predetermined distance 42 from an undeflected light path 44. Predetermined distance 42 may be related to an angle 46, measured between undeflected light path 44 and the path of output image 38. Angle 46 generally may be equal to two times angle 34 of image shifting surface 16 with respect to plane 36. Mathematically, distance of deflection 42 (D) may be equal to two times angle 34 (theta 1) times the distance 48 (L) from image shifting surface 16 to image plane 40, times a constant (K) (which is equal to 1.0 when there is no projection lens), times the cosine of an angle of rotation 50 (theta 2) of image shifter 18 about rotational axis 32, as represented by the equation:
D=2 (theta 1)LK cos(theta 2) Equation 1
In the embodiment shown, distance 48 is shown extending from image plane 40 to plane 36 at a position on image shifter 18 aligned with rotational axis 32, in contrast to other locations along plane 36 or along image shifting surface 16 which may be chosen in other embodiments. Measurement of distance 48 at this position on plane 36 yields accurate data from Equation 1 because distance 48 is generally much greater than the width of surface 16 as measured in plane 36. In one embodiment, distance 48 may be several feet whereas the width of surface 16, as viewed in
Angle of tilt 34 (theta 1) of surface 16 and angle 50 (theta 2) of rotation of image shifter 18 may be chosen so that the distance of deflection 42 (D) of output image 38 is sufficient to provide an increased resolution of a final image displayed on image plane 40, when compared to input image 14, as will be described with respect to
Display system 10 may also include a projection lens 39 (shown in dash lines in
Still referring to
Accordingly, in Equation 1 listed above, distance of deflection 42 (D) can be set to 0.354 to determine a desired angle 34 of image shifting surface 16, which will yield four pixel positions 52-58, each which are offset one half pixel width 60, 61 from one another. As stated earlier, the four pixel positions 52-58 are achieved by rotating image shifting surface 16 about rotational axis 32 with image shifting surface 16 inclined at angle 34 with respect to plane 36 that is perpendicular to rotational axis 32. The four pixel positions 52-58 shown in
Angle 34 of image shifting surface 16 may be set at any desired angle to achieve a pixel shift a distance other than one half a pixel width, as may be desired for a particular application. For example, it may be desired to provide a plurality of pixel positions wherein each pixel is shifted a total of one third a pixel width with respect to one another.
The actual width of the pixels of the system may also be chosen as suited for a particular application. For example, a width 78 of a pixel 52 may be 50 microns such that half a pixel width 60, and a desired pixel deflection distance 42 may be 25 microns. In another embodiment, a width 78 of a pixel 52 may be one half inch, and a desired pixel deflection distance 42 may be one quarter inch. Accordingly, angle 34 may be any angle calculated to achieve the desired deflection distance 42 of the pixels, and may be as small as one thousandth of a degree, or several degrees, for example. In such cases where angle 34 is less than several degrees, distance 48 measured between image plane 40 and plane 36 may be substantially the same as the distance between image plane 40 and image shifting surface 16 for purposes of Equation 1.
Referring again to
In another embodiment, the image shifter 18 is held about the perimeter inside a large bearing which allows the optical axis of input image 14 to be coincident with the axis of rotation of image shifter 18 such that the projected image passes through the center of a rotating skewed transparent disk. This arrangement may reduce distortion of the final image. In another embodiment, the system may include a time varying distortion correaction that is applied to the image to compensate for artifacts introduced by the shifting system.
The foregoing description of embodiments of the invention have been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variation are possible in light of the above teachings or may be acquired from practice of the invention. The embodiments were chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments and with various modification as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto and their equivalents.
